At least seven Marines are dead and another seven are injured after an accident Monday night in Nevada in which a mortar round exploded inside an artillery tube, military officials tell NPR's Tom Bowman.

The Marines were taking part in a live-fire exercise, those officials say. "Shell fragments, I'm told, killed almost three [Marines] immediately," Tom says. The others died before they could be evacuated to a hospital.

The Reno Gazette-Journal says the accident happened at the Hawthorne Army Depot, "about 135 miles southeast of Reno." Those killed, officials tell Tom, were from the 9th Marine Regiment out of Camp Lejeune, N.C.

"The identities of those killed will be provided 24 hours after primary next of kin notification. The status of those injured will be provided as it becomes available.

" 'We send our prayers and condolences to the families of Marines involved in this tragic incident. We remain focused on ensuring that they are supported through this difficult time,' said Maj. Gen. Raymond C. Fox, II MEF commanding general. 'We mourn their loss, and it is with heavy hearts we remember their courage and sacrifice.' "

Update at 5:39 p.m. ET. Blanket Suspension Of 60 mm Mortars:

Reuters reports the U.S. Marines have ordered a blanket suspension of 60 mm mortars. Marine Corps spokeswoman Capt. Kendra Motz said in a statement to Reuters that the suspension is in effect "until [a] review is complete."